Interactive or on-line advertising provides opportunities for advertisers to target their advertisements (“ads”) to a receptive audience. For example, the contents of user-inputted queries have been used by search engines to deliver relevant ads in conjunction with search results, the relevancy being a function of the query inputted by the user.
Certain tools exist to assist advertisers in targeting advertisements. For example, the web-based application, Google ADWORDS, permits an advertiser to identify certain web-sites that contain certain subject matter, that are listed in certain pre-defined categories, or which are similar in content to a given URL.